In early September I visited a remarkable organic farm on the coast of California. This farm has been in organic production for about 30 years, and its harvests of mostly organic tomatoes have been marketed through a variety of outlets in Northern California.
I arrived on the day picking had just begun on a sloping tomato field about 6 acres in size. The crop was exceptionally clean, with virtually no insect damage and few weeds. Minimal, organically approved control measures had been used, including applications of sulfur and releases of trichogramma (beneficial wasps), along with many hours of hand weeding.
One of every dozen-plus fruits had minor, cosmetic blemishing on the skin, typically where the tomatoes contacted the soil. Otherwise, the tomatoes were picture perfect. I can also vouch for their organoleptic quality, from a first-hand eating experience at a dinner during my stay. These tomatoes also, no doubt, contain markedly higher levels of health-promoting phenolic acids and Vitamin C, for reasons discussed in an earlier blog (“A Tale of Two Tomatoes,” February 23, 2013).
The grower has since reported that the field produced about 30,000 pounds of tomatoes per acre.
Farmers in other tomato-producing regions often produce substantially more per acre. My friend and colleague Madeline Mellinger runs Glades Crop Care (GCC), South Florida’s major independent crop consulting firm. She and the GCC staff scout and advise farmers on pest management across about 11,000 acres of tomatoes each year. In their neck of the woods, conventionally grown tomato yields average 50,000 pounds per acre, and in all but unusual years, range from 35,000 to 65,000 pounds/acre. Yields of 60,000 pounds per acre are common.
So what’s the big deal about a 30,000 pound per acre organic tomato yield in sunny California, when Florida (and some other California) growers often produce twice that per acre?
This was a dryland field of organic tomatoes – no, none, zero supplemental irrigation had been applied. The field was planted in April. Detailed weather data is accessible from a nearby weather station, which I accessed upon return to my office.
On August 6th and 7th, the last measurable rainfall had fallen in the area (0.02 inches, or two one-hundredths of an inch, i.e. almost none). July rainfall totaled 0.16 inch, and 0.04 inch fell in both May and June. A far-below average 0.45 inch fell in April, and only 1.12 inches came in March, usually one of the year’s wettest months.
Total precipitation for the 2014 production season was 1.83 inches. On California’s irrigated fresh market tomato fields, around 30” of irrigation water is applied to bring a crop to market, and according to the USDA, average yields are about 35,000 pounds per acre.
Organic production + 1.83 inches of rainfall = 30,000 pounds of tomatoes.
Conventional production + 30 inches of irrigation water = 35,000 pounds of tomatoes.
If a drought-weary California is forced to look for new ways to conserve water, the performance of this organic farm is both impressive and hopeful, given that it produced over 16,000 pounds of tomatoes per inch of rainfall. On a typical, irrigated, fresh market tomato field in California, experienced growers harvest about 1,200 pounds of tomatoes per inch of irrigation water, and somewhat less than 1,000 pounds per inch of rainfall-plus-irrigation water.
How could 30,000 pounds of tomatoes per acre be harvested on a field receiving so little rainfall?
It’s all about the soil. Over the last 30-plus years, this field has been in a complex rotation, with ample amounts of added organic material and routine cover cropping. The organic matter content of the soil has been increased about two-fold – from around 1.5% to about 3% — promoting rapid water infiltration (when it rains), as well as enhancing the soil’s water holding capacity.
So what does this un-irrigated, organic tomato field have to do with feeding the world?
Governments around the world are urging people to increase consumption of fruits and vegetables to at least four servings per day (the USDA recommendation is 5-8 servings/day). The population of California is currently 38 million, so each and everyday, the good citizens of the State should be consuming at least 152,000,000 servings of fruits and vegetables. Surely, mankind does not live by tomatoes alone, but for the sake of making an important point, bear with me.
According to the USDA, one serving of fresh tomatoes weighs 90 grams, or 0.19842 pound (i.e., there are about five servings in one pound of tomatoes). Accordingly, 1,005 acres of similarly managed, organic tomatoes yielding, on average, 30,000 pounds per acre, would produce enough tomatoes to feed 38 million Californians four servings of this vegetable for one day. Year-round, at the same yield level, only 366,943 acres would be needed to assure 38 million Californians get their four servings of fruits and vegetables a day.
The surface area of California is about 101 million acres, of which about 30 million acres are classified as farmland. About 6 million acres in California are regarded as “prime” farmland. Over 500,000 acres of California land are planted to cotton most years, and another 1.5 million produce hay. Clearly, finding 366,943 acres to produce enough fruits and vegetables (F+Vs) for all Californians should not be a major problem, at least not for a very long time.
For 314 million Americans, and the 7 billion on Planet Earth, less than 3% of available, high quality agricultural land would be required to assure production of at least four servings of F+Vs a day, per capita, year round.
Doing so, and getting the tomatoes, citrus, berries, and potatoes to the people who need them, including the poor, remains an enormous challenge, but not because of land shortages, lower yields on organic farms, or even persistent drought. In years when drought, or too much rain and flooding, or an untimely freeze, reduces fruit and vegetable production in one region, other areas can pick up at least some of the slack. And through new methods to preserve and store F+Vs, the nation could (and probably will someday) create a strategic F+V reserve.
As climate change and severe drought become more commonplace, the importance of building soil quality as a hedge against catastrophic crop failure will grow. Experience and insights gained on long-term, well-managed organic farms will provide a benchmark of what can be accomplished and how healthier, richer soil can serve as a buffer against climate extremes. And this will promote global food security, one field at a time.